Devices for picking up loads can be integrated, for example, into a forklift or can be configured as an add-on accessory that is or can be attached to a piece of equipment such as, for instance, a forklift. These devices usually have two load pick-up elements that can be moved relative to each other and that can be in the shape, for example, of two fork tines that can be moved relative to each other. The mobility of the fork tines allows users to adjust the position of the fork tines to the width of an object that is to be picked up or to recesses in said objects into which the fork tines can be inserted. With the known approaches, this is done, for example, with rail systems and hydraulic drives, as a result of which the fork tines can be moved to the left and to the right and, at the same time, can be moved toward each other or away from each other, so that there are two maximum positions for the load pick-up elements. In one maximum position, the two fork tines are arranged in the middle, whereas in the other maximum position, each of the two fork tines is in an outermost position and the two fork tines are at a maximum distance from each other. Examples of known approaches are described in U.S. Pat. No. 3,424,328 and in British patent GB 750,793.
The known approaches described above are suited for transporting loads that have been placed onto conventional pallets such as, for example, Euro pallets, whereby the known load pick-up devices are adapted to the dimensions of these pallets. In certain applications, however, the transport of loads using the prior-art approaches is hardly or not at all possible, when the load to be transported is not, for example, on a Euro pallet but rather on a relatively narrow base or on a surface with a small footprint and is thus narrower than the frame or the width of the forklift. If such a load is, for instance, in a truck, container or warehouse very close to a wall or to another object, then it cannot be picked up and transported away by conventional load pick-up systems, or else cannot be put down at the desired position near another object to begin with, since the movement of the forklift is hindered by the side wall and, with the prior-art approaches, the fork tines cannot be moved so far to the side. In such application cases, it might only be possible to move a single outer fork tine underneath the load base in order to pick up the load and to subsequently transport it away using only this single fork tine. However, transporting loads away with a single fork tine is associated with balance problems that could cause the forklift to tip over or the load to fall off the fork tine, so that, also for safety reasons, it is generally not permissible or envisaged to transport loads away using a single fork tine.
German Preliminary Published Application No. DE 36 32 031 A1 discloses an attachment for a forklift with which the fork tines are suspended on a fork carrier plate and, in the unloaded state, they can be moved sideways by hydraulic cylinders, independently of each other. Thus, with the device disclosed there, it is also possible to move both fork tines, for example, to one side of the fork carrier plate so that narrow loads that are, for example, on a pallet directly against a wall such as a container wall can be picked up with a forklift. However, the fork tines cannot be moved past the cylinder housing that drives them and they cannot be positioned in front of the cylinder housing that drives them, as a result of which it is only possible to a limited extent to move an individual fork tine over to the other half of the fork carrier on which the other fork tine is located. Moreover, since the fork tines of this device can only be moved when they are not carrying a load, after a load that is arranged in this way has been picked up, it also has to be transported in the same, asymmetrical position. This can lead to stability problems. The document proposes overcoming this problem by installing the device for individually moving the fork tines onto a known side-movement device. Such side-movement device can move both fork tines together, even under load. The distance of the fork tines relative to each other cannot be changed with such a device. If both functions, namely, the independent sideways movement of the two fork tines relative to each other and the joint sideways movement of both fork tines under load, are to be realized, then the two devices have to be combined with each other. However, if both of these devices have to be installed on the forklift, their additional intrinsic weight diminishes the load-bearing capacity of the forklift. Moreover, the space requirement of the forklift itself is increased, leading, for instance, to problems in maneuvering in tight spaces in warehouses. Furthermore, the two devices are expensive. Another drawback of this approach is the fact that conventional forklifts only provide two hydraulic connections in the form of two pairs of hydraulic lines at the attachment site of the load pick-up element, whereas three separate hydraulic connections are used for the combination of the two devices.